From: Paul Eggert <eggert@cs.ucla.edu>
Date: Mon, 4 Dec 2006 07:23:36 +0000 (+0000)
Subject: * lib/mkdir-p.c (make_dir_parents): Fix race condition when making
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d7df32475ce350a132c7c842e192d52780eea129;p=pspp

* lib/mkdir-p.c (make_dir_parents): Fix race condition when making
a directory that is about to be chowned.  Such a directory's
initial file permissions should permit the owner only and this
should not be changed until after the chown, since the group and
other bits would be incorrect if they granted permission before
the chown.
---

diff --git a/ChangeLog b/ChangeLog
index 51eec8691f..b6d4c6b721 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 2006-12-03  Paul Eggert  <eggert@cs.ucla.edu>
 
+	* lib/mkdir-p.c (make_dir_parents): Fix race condition when making
+	a directory that is about to be chowned.  Such a directory's
+	initial file permissions should permit the owner only and this
+	should not be changed until after the chown, since the group and
+	other bits would be incorrect if they granted permission before
+	the chown.
+
 	Fix porting problem for iswctype reported by Georg Schwarz in:
 	http://lists.gnu.org/archive/html/bug-coreutils/2006-12/msg00017.html
 	* lib/fnmatch.c (WIDE_CHAR_SUPPORT): Require HAVE_ISWCTYPE, too.
diff --git a/lib/mkdir-p.c b/lib/mkdir-p.c
index 19b962bf0f..a927d5d571 100644
--- a/lib/mkdir-p.c
+++ b/lib/mkdir-p.c
@@ -115,7 +115,14 @@ make_dir_parents (char *dir,
 
       if (0 <= prefix_len)
 	{
-	  if (mkdir (dir + prefix_len, mode) == 0)
+	  /* If the ownership will change, create the directory with
+	     more restrictive permissions at first, so unauthorized
+	     users cannot nip in before the directory is ready.  */
+	  mode_t mkdir_mode = mode;
+	  if (! (owner == (uid_t) -1 && group == (gid_t) -1))
+	    mkdir_mode &= S_IRWXU;
+
+	  if (mkdir (dir + prefix_len, mkdir_mode) == 0)
 	    {
 	      announce (dir, options);
 	      preserve_existing =
@@ -126,7 +133,10 @@ make_dir_parents (char *dir,
 		 | (mode & S_IRUSR ? SAVEWD_CHDIR_READABLE : 0));
 	    }
 	  else
-	    mkdir_errno = errno;
+	    {
+	      mkdir_errno = errno;
+	      mkdir_mode = -1;
+	    }
 
 	  if (preserve_existing)
 	    {
@@ -163,7 +173,6 @@ make_dir_parents (char *dir,
 		    }
 		  else
 		    {
-		      mode_t mkdir_mode = (mkdir_errno == 0 ? mode : -1);
 		      char const *subdir = (chdir_ok ? "." : dir + prefix_len);
 		      if (dirchownmod (fd, subdir, mkdir_mode, owner, group,
 				       mode, mode_bits)